Sound recording system



Jan. 17, 1933. s. KAHN SOUND RECORDING SYSTEM Filed Feb. 25. 1929 a J, e 10 1 6 a O a a l IAI/C/ C ma flifa lzey Patented Jan. 17, 1933 UNITED TA S SAMUEL KAH'N, or NEW YORK, 1v. Y., ASSIGNOR or ONE-THIRD TOMONROE FRIEDMAN 7 AND TWO-THIRDS 'IO ANTI-ION WILLIAM 'DELLER,

souivnniaconnms s s'rEM I Application filed rebma 25, 1929, se iai"i rb.a42,'a3a. I p

This invention relates to'gsound-recording I systems and "more particularlytotheart of recording sound on a photographic film and has for. its: object the provision of an improved system. f v I Heret'ofore vari-ous'systeins have-been employedv for recording sound by translating I sound waves into light" effects which were made effectiveupon atraveling 10 film. In this manner Variations in theintensity or the amount of light wh1ch were effective upon the film-were acoustically controlled. The systemsthus far proposed were all objectionable in that very rapid variations of light could not be obtained. Some systems were defective 1n that there was a mechanical distortion due to resonance. Other systems were too sluggish and would not respond practically instantaneously 'tosound, electric current and light effects.

I have discovered a system which is free from the "objections noted heretofore and which is a substantial improvement over prior systems.

In accordance with my invention I provide asystem of recording sound on photographic.

film whichis accurate, reliable and sensitive. With my improved system'it is possible to obtain fidelity of translation of sound Waves into electric currents and light effects whereby practically all of the sound from'the human voice or from'various instruments, including the melodious over-tones, may be faithfully recorded, Generally speaking, my invention contemplates providing a device which is very sensitiveto sound and'to electric currents andwhich is capable of causing the emission of light which changes practically instantaneously with changes of electric current and sound. In this manner it is possible to make a faithful record of 11111816, human voice, or other sounds on a photographic film-and it is possible to obtain practically perfect synchronism between the individual pictures of a motion picture and accompanying sound.

'My device is of such a construction that I may use a standard size motion picture film with standard size picture's thereon and I may record the sound'on the film located to the I recordonthe two sides order to get special results, such as music photographic right or to the-left of the pictures and preferably on the film situated between the outermost side'of the pictu-res and the innermost side of the perforations. In some instances of the pictures in from one source and the human voice or other sounds from other sources. Various other uses may be made of two recordsysuch as recording a 'frequencyrecord on" one side and'a volume record on thebtherside inorder'to will be free fror'ndistortion. The invention will be described mre in obtaina' reproduction which will betrue' andpanyin g drawing,in which 2'' n Fig. 1 is a sectional view of an embodiment of my invention as applied to the holder plate of a motion picture camera, certain well known'partsof the sake of clarity; A I

Fig. 2 is afragin'entary view of a portion of the camera holder plate with my improved record-width regulating device attached thereto; I

' Fig. 3 is anenlargedside view of thereflecting prism secured to the'vibrating arma detail-with particular reference to the acco'm .ture of my improved device illustrated in Fig. 1;

Figs; 4 and 5 vareendelevations of the prism shown in Fig. 3 with diff rent types of light windows;. j i

Fig. 6 is a plan view of the r armature su porting the light-reflecting prism Fig. 7 is a fragmentary portion of a stand- I ardphotographic film withstandard size pictures thereon and with wear my sound records located between the outermost sides-of the pictures andthe innermost sides ofthe film apertures;

F ig.- 18 is-afront elevation, somewhat fragmentary, of the camera-holder plate withmy record-width regulator attachedvthereto and with a portion of a film located in the rear thereofiand Fig. 9 is a'modified embodiment'of'myinvention. r Referring now more particularly to Fig. l, the numeral 1' designates a light-tight casing of my improved device whi'ch issec'uied the latter being'omitted for v magnetic coil it is possible to obtain appropriby meansof a wall 15 of the'pole plates 5 fyin net provided in the well-known manner I 5. Between thesesidesof the LL the motion pictures the microphone which is used inthe recording of the sound located near the music, the

and screws 15-11 to a film supporter vor plate 14 mounted within a camera (not shown). This film supporter, as is well known, is mounted an appropriate distance from the camera aperture, usually the distance of about 19 to 20pictures. Within the casing l'is mounted an electro-magnetic unit 2 which is composed of a U-shaped magwith pole plates shaped magnet and adjacent to the innerside an annularcoil 4 is located. Through the annular coil 4 and between the pole plates 5 an armature 7 projects as a cantilever arm from its mounting 3 which is rigidly secured to the sides of the U-shaped magnet 2. v

The electromagnetic coil 4cis connected to a source of electrical energy such as batteries 36-a and to amlcrop apparatus designated as 36. The microphone, of course, can be carried to and placed at any remote point or location where the sound is being generated. In this way, it

is possible to have the camera which is taking located in one place and talking actors or the like. By properly magnifying the electrical currents received from the microphone in a manner well understood in the art, electrical currents of practically any desired value may be impressed on the electromagnetic coil. Due to variations in the electrical current impressed on the electroate variations in the electro-magnet field. The variations in the electro-magnetic field cause vibrations of the armature 7. These vibrations are thus proportional to the modulations of sound impinging upon the microhone. i

The vibrating armature is provided at its free end with a light reflectingprism 6 which issecurely mounted over a light aperture 26. The prism may be secured in any appropriate manner such as by cementing with an adhesive binder or by a'clip fastened around the bottom of the armature and the sides and or top. With this arrangement the prismwill vibrate with the'vibrating armature. Faces a,'b andsd (see Figs. 35) of the prism are preferably completely covered with someopaque light-reflecting substance like a silvered mirror. Face 6 is similarly covered with the exception of the pin hole or bulls eye 24 or slit 25 which is left uncovered for the emission of light from within the prism. This light, is supplied from a constant source of light such as an electric bulb 8 which is fitted in a condenser tube 13 provided with condenser lenses 9 and 10. Adjustment of the condenser may be had by grasping knob 11 and moving the outer portion of tube 13 in order to concentrate the light within the hone and suitable ampli-' prism. Electric bulb 8 may be energized in any well known way as by the use of an elec v is reflected f om the inner face of the prism through the bulls eye 24: or slit 25 andisoundrecording window 22 in the film supporterv 14 to the photographic film 16. Thesound is recorded in recordportion 19 whichis located betweenthe'outermost sides of the picturesand the innermost sides of the rectangular holes for the star-wheels of the projecting camera. lnsome instances I prefer to pro vide a regulator 22-a for controlling the width of the bands or waves of sound recordedon the film. As may be seen fromFigs. 2 and I 8 the regulator 22-0, may be adjusted back and 1 forth by use of adjustingscrews 23. v is to be observed that with the aforesaid organiza tion it is possible to use a standard motion picture film with standard-size pictures thereon and to record the sound. in that portion of the film situated between the outermost 2 sides of the picture and the innermost sides of the starwheel guide holes. In the operation of rny recording device the mot on p cture camera is operated in the usual manner and the e0 mproved sound- '4 microphone is positioned. nearthe scene of action, music, is to be recorded. v vVith myarrangement the camera maybe located in one positionwhere as the microphone may be located some remote point therefrom. As the sound to be recorded becomes effective upon themicrophone, electrical currents set upin the microphone system which cause a variation in the strength ,of the electro magne't. The variations in the electro-magnet set' the armature with its prism into vibration which continues as long as sound is being transmitted through the microphone. Due to the vibrations of the armature light issuing from. the bulls eye 24 or slit 25 isvibrated back and forth about a central line or axis (shown by a full line in Fig. 1). This vibrating light affects the or. whatever source ofsound 7;

photographic film in a well known manner and makes a zig-Zag record line which looks to the naked eye like bands 21. Sound can .115

film 27 upon which two sound records have been recorded, a' record 21 on the right-hand side of the film and a record 28 on the left- 7 hand side. As explained heretofore these records may be used for any variety of purposes. For nstance, one can be; the record of music and the other that of the human voice. Many other variations are possiole as one skilled in the art will readily understand.

A modified embodiment of my invention is illustrated in Fig. 9. This embodlment has the same fundamental principles incorporated therein as the structure described hereinabove except a phone type of vibrator is used instead of an electromagnetic type. In the modified embodiment the microphone system Stiis connected to a magnetic phone coil 35 which is provided with a pole 39. This magnetic coilis mounted on insulators 38 within casing 29 which is screwed on to or otherwise secured to housing 80. Clamped between this housing 30 and the casing 29 is a diaphragm D provided with a mirror-like polished or silvered reflective surface.

Casing 30 is secured to a film supporter, or plate l t by means of a plurality of screws 37 or the like and is cast so as to provide a mounting M for a light 81 and condenser 34 with lenses 32 and 33 and a light tube L at an oblique angle to said mounting. Electrical energy is supplied to electric light 31 by means of batteries 40. When the electric light is energized a light beam is emitted to the diaphragm and is reflected therefrom in approximately a central line of tube L1 This line passes through sound-recording aperture 22 and lies about in the middle of the sound record 21.

When motion pictures are, taken the sound is transmitted to the microphone which causes variation in the electro-magnetic field and a vibration of the diaphragm. As the diaphragm vibrates the reflected line oscillates back and forth and causes a variation in the light impinging upon the film 16. The light waves are depicted in somewhat exaggerated form asvzig-zag lines, although in a finished film the lines are very close together and appear like a series of transverse lines or hands zig-zagging back and forth about a central line or axis.

Although I have described specific embodiments of my invention it is to be understood that the invention is not restricted to such particular embodiments. Various modifications thereof in detail and in the arrangement of the parts may be made by those skilled in the art without departing from the invention as defined in the claims. For example, the armature may be developed at its free end as a light reflectingsurface so that the necessity of having a special prism for this purpose may be dispensed with. The metal of the armature may be electro-plated with nickel and/or chromium to provide a mirror-like reflecting surface.

I claim:

1. In apparatus for recording motion pictures and sound on a photographic film that improvement which comprises'in combination a microphone, a source of electrical energy for actuating said microphone, an electro-magnetic coil connected to said microphone and source of energy whereby modulations of sound impinging upon said microphone are converted into electro-magnetic variations in said 0011, an armature located closely'adjacen't to said'coil. s'ohajsv to be'vibrated V by the said electro magnetic; variations, saidparmature being fixed atone end and'adapted to-be acted upon magnetically at'. an intermediate portion thereof by the aforesaid electro-magneticcoil While. the other end is freeto vibrate, a light aperture provided insaid' armature adjacent to the free end thereof; light reflecting prism mounted over the light apferture'of said armature and capable of vibrating therewith, said prism bein covered practically completely with an opaque substance and having a small aperture for light on one faceand a pin hole on aface at right angles thereto for the emission of a'sh'arp, concentrated, intense beam of light reflected from the inclined face of the prism; a source of light positioned to direct a beam of light on said light-reflect ing prism through said small light aperture, and a sound aperture incorporated in the film supporter of the recording apparatus in alignment with a beam of light normally reflected by said light-reflecting means Whereby the light reflected by the vibrating light reflecting means on the armature is effective for making a sound record on the photographic film. i

2. In apparatus for recording motion pic- I tures and sound on a photographic film that improvement which comprises in combination a microphone, a source of electrical energy for actuating said microphone, an electromagnetic coil connected to said microphone and source of energy whereby modulations of sound impinging upon said microphone are converted into electro-magnetic variations in said coil, a cantilever armature located closely adjacent to said coil so as to be vibrated by the said electro-magnetic variations, said armature being fixed at one end and adapted to be acted upon magnetically at an intermediate portion thereof by the aforesaid electro-magnetic coil while the other end is free to vibrate, a. light aperture provided in said armature adjacent to the free end thereof;

light-reflecting prism fixedly mounted over said lightlaperture of said armature and capable of vibrating therewith, said prism being covered practically completely with an opaque substance and having a small aperture for light on one face and a pinhole on a face a at right angles thereto for the emission of a sharp, concentrated, intense beam of light reflected from the inclined face of the prism; a source of light positioned to direct a beam of light on said light-reflecting prism through said small aperture, and a sound aperture incorporated in the film supporter of the recording apparatus in alignment with a beam of light normally reflected by said light-reflecting meanswhereby the light reflected by the vibrating light-reflecting means on the armature is eflective for making a sound record on the photographic film.

o 3.111? apparatus for recording motion pictures and sound the combination comprising an electro-magnetically vibrated armature having light-reflecting prism mounted over a light aperture at the free end thereof and in- "cluded' in a microphone-circuit, said prism being covered practically completely with an opaque substance and having a small aperture' for light on one face and a pin hole on a "10 face at right angles thereto for the emission of a sharp, concentrated, intense beam of light reflected from the inclined face of the prism, a moving photographic film, and means for causing light to impinge on said vibrating armature for reflection to said film in accordance With variation of sound received by said microphone.

In testimony whereofI have hereunto set my hand. SAMUEL KAI-IN. 

